1. Technical Field
The present invention pertains to radio paging receivers, and more particularly, to a circuit and process for displaying indications of urgent calls with a radio paging receiver.
2. Background Art
Generally, a radio paging receiver such as a personal pager, is included in a one-way communication system (i.e., a radio paging system) capable of receiving a call provided by a caller. Currently available radio paging systems have a central paging terminal transmitting Post Office Code Standardization Advisory Group (i.e., POCSAG) coded radio signals to individual radio paging receivers or to groups of radio paging receivers via an antenna. A caller dialing the unique number assigned to a pager, is typically connected via public lines and a central office telephone switching system to the paging terminal. The paging terminal processes the unique number received via the public line from the caller, and transmits as a radio signal, a unique code also assigned to the pager sought by the caller.
The pager detects the transmission of its unique code, and as shown in U.S. Pat. No. 3,742,481 to Douglas W. Nickerson, stores incoming paging calls. Currently available pagers store as a received call, among other items, any message component of the radio signal received. Such received calls are stored in the order in which they are received by the pager and the person wearing the pager can, subsequent to the reception and storage of the call, confirm the reception of the call and read the message component of the call; if the pager has received a large number of calls however, the user will normally read all of the message components of the received calls. U.S. Pat. No. 4,438,433 for Multiaddress Pager With A Call Storage and Priority Paging Option to George W. Smoot, et al. endeavors to bypass the store-and-subsequent-read routine operation of pagers by using a decoder and shift register memory adapted to generate a priority status level signal when the incoming signal is an emergency call and a non-priority status level signal when the incoming signal is a non-emergency call, and to thereby effect an immediate reading of emergency-type signals. In some situations (e.g., a physician currently engaged in operating room surgery) however, effecting an immediate reading of a message upon reception of one, or worse, a succession, of emergency-type signals, does not concomitantly enable the person wearing the pager to either view or respond to the accompanying message.
U.S. Pat. No. 4,949,085 for Prioritization Of Stored Messages In A Digital Voice Paging Receiver to Kenneth D. Fisch, et al., envisions an embodiment of a pager storing messages in a predetermined priority, with replacement of one stored message by an incoming message when the priority status of the incoming message is greater than the priority status assigned to the memory slot in which the stored message is held (e.g., whether the stored message has a status designation of protect, unread, read or empty). In this scheme however, if all message slots within a queue contain stored messages, rather than risk the loss of an incoming message, the oldest message that has already been read, or alternatively, if no unread messages are stored, the oldest message (i.e., the message having the highest queue order) is deleted to accommodate storage of an incoming message with greater priority status. The chronological order of the undeleted messages within the queue is preserved however. Consequently, in this scheme the message component of an urgent call could be deleted even though never having been read by the wearer of the pager, if that message has the highest queue order, an occurrence which is not necessarily desired particularly when the pager receives a number of calls exceeding its storage capacity within a short interval.
The pager described in U.S. Pat. No. 5,225,826 for Variable Status Receiver to DeLuca et al, for example, uses a pager equipped with a real time clock, and transmits calls with three message status signals followed by three time signals and a message; the message, status and time signals provide a basis for establishing a default status for the message and for changing the status of the message with the passage of time. DeLuca '826 contemplates responding to calls received on the basis of its status, and accommodating storage of the message component of a newly received call by deleting previously stored messages on the basis of the current status associated with the stored message.
In such currently available pagers, and as taught by Fisch '085, the order of storage of messages within a queue is independent of the status of the message, with messages stored in a plurality of message slots within a memory, and visually display messages in chronological order from the most recently received message to the oldest message without regard to status of the message slots (unread versus read). Moreover, even if the same call has been repeatedly received, the user normally reads the same message stored for each occasion on which that call was received in order to view all of the message components of the other calls received and stored. Furthermore, even if the caller causes a call (i.e., an "urgent call") to be transmitted to the pager to inform the pager of a very urgent situation, that urgent call is processed for storage with the same equality as other, non-urgent calls. As a result, it can be difficult to alert the wearer of the pager to the urgent situation.
Generally then, pagers currently commercially available inconveniently store all calls received on a space available basis, albeit with deletion of either previously read messages or the oldest message within the queue to accommodate storage of incoming calls, despite repetition of some calls, in a queue arranged in chronological order, and visually display calls received in the order (e.g., typically, in chronological order) in which those calls have been received, and hinder the ability of the wearer of the pager to quickly read a message for an urgent call.